SolvitDB: added .svt file reading

lib/solvitdb.lua

@@ -0,0 +1,99 @@
+local solvitdb = {}
+
+local fs = require("filesystem")
+
+local function checkValidityAndOpen(path)
+  local handle = assert(fs.open(path))
+  local data = assert(handle:read(8))
+  if data:sub(5, 8) == "RTFM" then
+    local patLength = string.unpack("<I4", data:sub(1, 4))
+    return handle, patLength
+  else
+    error("missing magic")
+  end
+end
+
+local function readPat(handle, patLength)
+  -- This needs the handle to be at byte 4
+  local data, tmpdata = ""
+  repeat
+    tmpdata = handle:read(patLength - #data)
+    data = data .. (tmpdata or "")
+  until not tmpdata
+  local packages = {}
+  for packageData in data:gmatch("(.-%.....);") do
+    packages[packageData:sub(1, -6)] = string.unpack("<I4", packageData:sub(-4, -1))
+  end
+  return packages
+end
+
+function solvitdb.create(path)
+  checkArg(1, path, "string")
+  local handle = assert(fs.open(path, "w"))
+  assert(handle:write("\0\0\0\0RTFM"))
+  handle:close()
+end
+
+function solvitdb.set(path, name, data)
+  checkArg(1, path, "string")
+  checkArg(2, name, "string")
+  checkArg(3, data, "table")
+  local handle = checkValidityAndOpen(path)
+end
+
+function solvitdb.get(path, name)
+  checkArg(1, path, "string")
+  checkArg(2, name, "string")
+  local handle, patLength = checkValidityAndOpen(path)
+  local pat = readPat(handle, patLength)
+  assert(pat[name], "could not find package in PAT")
+  handle:seek(pat[name])
+  local data, tmpdata = ""
+  repeat
+    tmpdata = handle:read(math.huge)
+    data = data .. (tmpdata or "")
+  until data:find("\n", 1, true) or not tmpdata
+  if not data:find("\n", 1, true) and not tmpdata then
+    error("hit unexpected EOF")
+  end
+  data = data:match("^(.-)\n")
+  local output = {}
+  if data:sub(1, 1) == "P" then
+    output.type = "package"
+  elseif data:sub(1, 1) == "G" then
+    output.type = "group"
+  elseif data:sub(1, 1) == "V" then
+    output.type = "virtual-package"
+  else
+    error("unknown package type")
+  end
+  data = "." .. data:sub(2, -1)
+  for series in data:gmatch("%.([dDcp][^.]*)") do
+    local seriesOutput
+    if series:sub(1, 1) == "d" then
+      output.dependencies = {}
+      seriesOutput = output.dependencies
+    elseif series:sub(1, 1) == "D" then
+      output.reverseDependencies = {}
+      seriesOutput = output.reverseDependencies
+    elseif series:sub(1, 1) == "c" then
+      output.conflicts = {}
+      seriesOutput = output.conflicts
+    elseif series:sub(1, 1) == "p" then
+      output.packages = {}
+      seriesOutput = output.packages
+    end
+    -- Finally a case where Lua's weird table linking shenanigans are actually useful
+    series = series:sub(2, -1)
+    for seriesItem in series:gmatch("[^;]+") do
+      table.insert(seriesOutput, seriesItem)
+    end
+  end
+  return output
+end
+
+function solvitdb.remove()
+
+end
+
+return solvitdb